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What Variables Best Describe Effective Resistance
Training?Toigo M, Boutellier U. New fundamental resistance exercise determinants of molecular and cellular muscle adaptations. European Journal of Applied Physiology. 2006; 97: 643-663.
Toigo and Boutellier’s major point is that the number of variables that have been used to describe resistance training has been limited. The typical variables have included resistance often defined as a percentage of a one maximum repetition (1RM), number of repetitions, sets per exercise or muscle group, and frequency of training per week. Using “Let’s treat ourselves like valuable athletes.only a few descriptive variables, they claim, limits the science and practice of resistance training. This is because there are other variables that may differentially impact muscle adaptations at the molecular or cellular level. If the variable is not described, it can not be studied. If there are other variables that are needed to adequately describe a protocol but are rarely if ever included in a protocol’s description, then the protocol can not be replicated and assessed in another study. Science rests on replication of the effects of different treatments and protocols. From the perspective of the trainee, if there are variables other than the familiar ones that can describe an effective protocol, we would like to know what they are. Then we could alter our own training protocol and possibly make it more effective. Toigo and Boutellier indicated that in describing any resistance training protocol, the following variables should be included because they may have an impact on muscle adaptations. Note that some of these variables are, in fact, ones that have been traditionally used and some are not. The 13 variables are:1. load as defined as percent of 1 RM; 2. number of repetitions; 3. number of sets per exercise or muscle group; 4. rest time in between sets; 5. number of training sessions per muscle group per week and overall number of training sessions; 6. the duration for use of a protocol in weeks or months (important to assess outcomes and replicate a study’s findings); 7.the number of seconds for the concentric and eccentric part of the repetition; 8. the rest in between repetitions; 9.the time under tension (TUT); 10. training or not training to volitional fatigue; 11. the range of motion for an exercise; 12. the recovery time between exercise sessions; 13. the precise form used in an exercise. Interestingly, a number of these variables such as TUT, repetition form and duration, and overall form have been discussed in this issue and in a number of recent issues. Of particular interest was the authors’ analysis of the size principle, TUT, and training to volitional fatigue. The analysis substantiated points made in the last issue and has direct application to training protocols. Toigo and Boutellier noted that for mammals there is a graded level of recruitment of motor units. The motor units are recruited from smallest to largest based on the requirement to complete a task. The requirement is the relative force requirement, i.e., the degree of effort needed to complete the task. In simple terms, as effort increases, smaller motor units are fatigued and larger motor units are additionally recruited to complete as much of the task (e.g., perform a few more repetitions) as possible before they too are fatigued. It has been assumed that in resistance training, it is important to train to failure (muscular exhaustion) because in that way motor unit recruitment is maximized. Based both on theory and some data, the authors go one step further. They indicated that as long as the exercise is performed to volitional muscular failure, a wide range of loads with a wide range of TUT’s will lead to similar maximally possible motor recruitment. Although not all adaptations require training to volitional muscular failure, maximal motor recruitment is a stimulus for protein synthesis, a building block for muscle adaptation. Different metabolic processes may be involved in widely different TUT’s such as 30 seconds compared to 90 seconds or perhaps even 180 seconds. However, based on the analyses by Toigo and Boutellier, it appears possible, given favorable genetic characteristics, to produce muscular hypertrophy without using a great deal of resistance provided training is performed to muscular failure. For example, assuming the same form and time for each repetition (4 seconds for the concentric part of the repetition, 4 seconds for the eccentric part with two seconds allotted to smooth transitions between concentric and eccentric parts of the repetition), performing 8 repetitions with a moderate resistance to muscular failure appears to be a similar stimulus for protein synthesis as performing the same exercise with a very heavy resistance so that four repetitions to muscular failure are performed. The very heavy resistance may increase the possibility of injury while use of the more moderate resistance may decrease the possibility of injury. In email notes to me on August 2 and August 20, 2006, Dr. Toigo confirmed, with some caveats noted later in the ‘bottom-line’ section, the interpretation you have just read of the review article. The perspective for understanding
Dr. Toigo’s points is this quote from him: ‘In resistance exercise it is not the goal to demonstrate strength but to specifically deliver tension to the target muscle. The more targeted the delivery is, the less resistance
can be used’.“The goal of resistance training is to deliver tension to muscle groups.”
Here are Dr. Toigo’s points: As mentioned in the article, motor unit (MU) recruitment is completed by approximately 50% of maximum voluntary contraction (MVC) in small muscles (such as adductor pollicis and first dorsal interosseus), and 70-80% of MVC in large muscle (such as biceps and deltoid). Thus, how the force output is regulated (recruitment vs. rate coding) seems to depend on the respective muscles. However, a certain threshold in terms of percent MVC (e.g. 80% MVC) must be met in order to achieve complete recruitment. In this context, complete does not mean, that all possible MU in the respective muscle have been recruited. Rather, it refers to those MU’s that can be voluntarily recruited as a function of the same (exercise) motor task that is undertaken in exactly the same way. If the threshold is met, fast progression through the fiber types occurs fast. If the threshold is met slowly, progression through the fiber types occurs slowly. Either way, the threshold is met. Thus, whether motor task-specific complete recruitment
is achieved depends on the resistive load at the onset of exercise but also on fatigue inroad. Exercising to volitional failure (only few know what this really means...) is not a prerequisite to meet the threshold. However, from a practical point of view, it is a more or less reproducible means for quantifying fatigue inroad. It is more likely that recruitment, and thus, progression through the fiber types is complete, when the exercise is performed to volitional failure. Moreover, sustaining the contraction above the threshold for complete MU recruitment until exhaustion will also affect issues related to MU rate-coding. In conclusion, as you said, resistance training programs can use a relatively wide range of loading and time under tension in order to attain complete recruitment, as long as the respective threshold is met. This threshold for complete recruitment is not exclusively, but more likely to be met if the exercise is performed to volitional failure (with anatomically perfect technique and slow movement velocity, avoiding rapid accelerations/decelerations).
Complete MU recruitment is an important determinant for the stimulation of muscle protein synthesis but it is one of several determinants for muscular adaptation. Thus, although similar stimulation of muscle protein synthesis can be achieved through different loading strategies, the adaptation effects might vary considerably. This is due to the different ‘cocktail’ of stimulatory cues that can be more or less specifically delivered to the muscle. In another section of the paper, Toigo and Boutellier indicated that ‘local hypoxia’ (decreased skeletal muscle oxygenation, for example through impaired blood supply) may be a stimulus for muscular hypertrophy. How an exercise is performed appears to influence oxygen and blood supply. Providing constant tension to a muscle group over a certain time may decrease blood supply and induce local hypoxia. For example, the effect may be produced by performing longer duration repetitions with very smooth transitions from the positive to negative and negative to positive part of the repetition. Pausing in ‘easy’ parts of a repetition such as locking the knees at the end of each repetition in the leg press or squat may reduce the effectiveness
of the training protocol. Such pauses enable the use of more resistance, possibly at the cost of effectiveness for muscular hypertrophy. Bottom-line: The two areas of analyses from this article are very intriguing. The analyses indicate that there needs to be more variables and greater specificity in describing resistance
protocols. The two analyses indicate why describing TUT and training or not training to failure is important, as well as describing the precise duration and form of each repetition. The analyses in these two areas also indicate that it is quite possible to activate the mechanisms involved in muscular hypertrophy without using a great deal of resistance. For example, putting these two areas of analyses together suggests that using moderate resistance, for longer duration repetitions with very smooth form and for a longer TUT may be a good stimulus for muscular hypertrophy. Based on these two analyses, here is a training perspective to consider. Suppose that an adequate stimulus for muscle groups is, in fact, as data suggest, one exercise performed to muscular failure. Perhaps, for larger muscle groups, one isolation movement (knee extension) and one compound movement (leg press) can be performed to failure is adequate, and for smaller muscle groups, just the one exercise (curl) performed to failure is adequate. Suppose also if there is anything to variation of exercises that you could perform routine ‘A’ and routine ‘B’ that altered exercises (e.g., squat for leg press). Frequency of training would then be based on simply your pattern of recovery that is influenced by individual factors, age, other exercise and physical activity performed, personal preferences, and motivation. Suppose based on the analyses by Toigo and Boutellier that in order to maximize your genetic potential for muscular hypertrophy, you never had to lift very heavy resistance. With the use of more moderate resistance, it is likely that recovery may be quicker than when heavy resistance is used. With moderate resistance, the chance of injury also may be less than when heavy resistance is used. Such a training protocol would hardly be ‘easy’ to perform. Because of the effort and great attention to form that are required, it is very ‘hard’. However, consider the efficiency, safety, and likely effectiveness of the approach. Do these analyses point to the effectiveness of ‘super slow’ training or the very first protocols developed by Arthur Jones? Although ‘further study is needed’, it is likely that repetitions need not be as long as 15 seconds and that likely an effective volume and frequency of training are greater than typically recommended by ‘super slow’ advocates. Effective protocols may be more similar to ones originally advocated by Arthur Jones decades ago but with much greater attention to form, a longer time under load, and less concern with the use of great amounts of resistance. There also is one major caveat. Different protocols and different TUT’s may produce similar outcomes, as noted, because the all have a common critical component. They all involve training to volitional fatigue that appears to optimize motor unit recruitment. However, current data do not support the notion every single possible training variable (see the list of 13 noted earlier) and nuance result in different kinds of strength, endurance, power, and muscular hypertrophy adaptations. ?
Training?Toigo M, Boutellier U. New fundamental resistance exercise determinants of molecular and cellular muscle adaptations. European Journal of Applied Physiology. 2006; 97: 643-663.
Toigo and Boutellier’s major point is that the number of variables that have been used to describe resistance training has been limited. The typical variables have included resistance often defined as a percentage of a one maximum repetition (1RM), number of repetitions, sets per exercise or muscle group, and frequency of training per week. Using “Let’s treat ourselves like valuable athletes.only a few descriptive variables, they claim, limits the science and practice of resistance training. This is because there are other variables that may differentially impact muscle adaptations at the molecular or cellular level. If the variable is not described, it can not be studied. If there are other variables that are needed to adequately describe a protocol but are rarely if ever included in a protocol’s description, then the protocol can not be replicated and assessed in another study. Science rests on replication of the effects of different treatments and protocols. From the perspective of the trainee, if there are variables other than the familiar ones that can describe an effective protocol, we would like to know what they are. Then we could alter our own training protocol and possibly make it more effective. Toigo and Boutellier indicated that in describing any resistance training protocol, the following variables should be included because they may have an impact on muscle adaptations. Note that some of these variables are, in fact, ones that have been traditionally used and some are not. The 13 variables are:1. load as defined as percent of 1 RM; 2. number of repetitions; 3. number of sets per exercise or muscle group; 4. rest time in between sets; 5. number of training sessions per muscle group per week and overall number of training sessions; 6. the duration for use of a protocol in weeks or months (important to assess outcomes and replicate a study’s findings); 7.the number of seconds for the concentric and eccentric part of the repetition; 8. the rest in between repetitions; 9.the time under tension (TUT); 10. training or not training to volitional fatigue; 11. the range of motion for an exercise; 12. the recovery time between exercise sessions; 13. the precise form used in an exercise. Interestingly, a number of these variables such as TUT, repetition form and duration, and overall form have been discussed in this issue and in a number of recent issues. Of particular interest was the authors’ analysis of the size principle, TUT, and training to volitional fatigue. The analysis substantiated points made in the last issue and has direct application to training protocols. Toigo and Boutellier noted that for mammals there is a graded level of recruitment of motor units. The motor units are recruited from smallest to largest based on the requirement to complete a task. The requirement is the relative force requirement, i.e., the degree of effort needed to complete the task. In simple terms, as effort increases, smaller motor units are fatigued and larger motor units are additionally recruited to complete as much of the task (e.g., perform a few more repetitions) as possible before they too are fatigued. It has been assumed that in resistance training, it is important to train to failure (muscular exhaustion) because in that way motor unit recruitment is maximized. Based both on theory and some data, the authors go one step further. They indicated that as long as the exercise is performed to volitional muscular failure, a wide range of loads with a wide range of TUT’s will lead to similar maximally possible motor recruitment. Although not all adaptations require training to volitional muscular failure, maximal motor recruitment is a stimulus for protein synthesis, a building block for muscle adaptation. Different metabolic processes may be involved in widely different TUT’s such as 30 seconds compared to 90 seconds or perhaps even 180 seconds. However, based on the analyses by Toigo and Boutellier, it appears possible, given favorable genetic characteristics, to produce muscular hypertrophy without using a great deal of resistance provided training is performed to muscular failure. For example, assuming the same form and time for each repetition (4 seconds for the concentric part of the repetition, 4 seconds for the eccentric part with two seconds allotted to smooth transitions between concentric and eccentric parts of the repetition), performing 8 repetitions with a moderate resistance to muscular failure appears to be a similar stimulus for protein synthesis as performing the same exercise with a very heavy resistance so that four repetitions to muscular failure are performed. The very heavy resistance may increase the possibility of injury while use of the more moderate resistance may decrease the possibility of injury. In email notes to me on August 2 and August 20, 2006, Dr. Toigo confirmed, with some caveats noted later in the ‘bottom-line’ section, the interpretation you have just read of the review article. The perspective for understanding
Dr. Toigo’s points is this quote from him: ‘In resistance exercise it is not the goal to demonstrate strength but to specifically deliver tension to the target muscle. The more targeted the delivery is, the less resistance
can be used’.“The goal of resistance training is to deliver tension to muscle groups.”
Here are Dr. Toigo’s points: As mentioned in the article, motor unit (MU) recruitment is completed by approximately 50% of maximum voluntary contraction (MVC) in small muscles (such as adductor pollicis and first dorsal interosseus), and 70-80% of MVC in large muscle (such as biceps and deltoid). Thus, how the force output is regulated (recruitment vs. rate coding) seems to depend on the respective muscles. However, a certain threshold in terms of percent MVC (e.g. 80% MVC) must be met in order to achieve complete recruitment. In this context, complete does not mean, that all possible MU in the respective muscle have been recruited. Rather, it refers to those MU’s that can be voluntarily recruited as a function of the same (exercise) motor task that is undertaken in exactly the same way. If the threshold is met, fast progression through the fiber types occurs fast. If the threshold is met slowly, progression through the fiber types occurs slowly. Either way, the threshold is met. Thus, whether motor task-specific complete recruitment
is achieved depends on the resistive load at the onset of exercise but also on fatigue inroad. Exercising to volitional failure (only few know what this really means...) is not a prerequisite to meet the threshold. However, from a practical point of view, it is a more or less reproducible means for quantifying fatigue inroad. It is more likely that recruitment, and thus, progression through the fiber types is complete, when the exercise is performed to volitional failure. Moreover, sustaining the contraction above the threshold for complete MU recruitment until exhaustion will also affect issues related to MU rate-coding. In conclusion, as you said, resistance training programs can use a relatively wide range of loading and time under tension in order to attain complete recruitment, as long as the respective threshold is met. This threshold for complete recruitment is not exclusively, but more likely to be met if the exercise is performed to volitional failure (with anatomically perfect technique and slow movement velocity, avoiding rapid accelerations/decelerations).
Complete MU recruitment is an important determinant for the stimulation of muscle protein synthesis but it is one of several determinants for muscular adaptation. Thus, although similar stimulation of muscle protein synthesis can be achieved through different loading strategies, the adaptation effects might vary considerably. This is due to the different ‘cocktail’ of stimulatory cues that can be more or less specifically delivered to the muscle. In another section of the paper, Toigo and Boutellier indicated that ‘local hypoxia’ (decreased skeletal muscle oxygenation, for example through impaired blood supply) may be a stimulus for muscular hypertrophy. How an exercise is performed appears to influence oxygen and blood supply. Providing constant tension to a muscle group over a certain time may decrease blood supply and induce local hypoxia. For example, the effect may be produced by performing longer duration repetitions with very smooth transitions from the positive to negative and negative to positive part of the repetition. Pausing in ‘easy’ parts of a repetition such as locking the knees at the end of each repetition in the leg press or squat may reduce the effectiveness
of the training protocol. Such pauses enable the use of more resistance, possibly at the cost of effectiveness for muscular hypertrophy. Bottom-line: The two areas of analyses from this article are very intriguing. The analyses indicate that there needs to be more variables and greater specificity in describing resistance
protocols. The two analyses indicate why describing TUT and training or not training to failure is important, as well as describing the precise duration and form of each repetition. The analyses in these two areas also indicate that it is quite possible to activate the mechanisms involved in muscular hypertrophy without using a great deal of resistance. For example, putting these two areas of analyses together suggests that using moderate resistance, for longer duration repetitions with very smooth form and for a longer TUT may be a good stimulus for muscular hypertrophy. Based on these two analyses, here is a training perspective to consider. Suppose that an adequate stimulus for muscle groups is, in fact, as data suggest, one exercise performed to muscular failure. Perhaps, for larger muscle groups, one isolation movement (knee extension) and one compound movement (leg press) can be performed to failure is adequate, and for smaller muscle groups, just the one exercise (curl) performed to failure is adequate. Suppose also if there is anything to variation of exercises that you could perform routine ‘A’ and routine ‘B’ that altered exercises (e.g., squat for leg press). Frequency of training would then be based on simply your pattern of recovery that is influenced by individual factors, age, other exercise and physical activity performed, personal preferences, and motivation. Suppose based on the analyses by Toigo and Boutellier that in order to maximize your genetic potential for muscular hypertrophy, you never had to lift very heavy resistance. With the use of more moderate resistance, it is likely that recovery may be quicker than when heavy resistance is used. With moderate resistance, the chance of injury also may be less than when heavy resistance is used. Such a training protocol would hardly be ‘easy’ to perform. Because of the effort and great attention to form that are required, it is very ‘hard’. However, consider the efficiency, safety, and likely effectiveness of the approach. Do these analyses point to the effectiveness of ‘super slow’ training or the very first protocols developed by Arthur Jones? Although ‘further study is needed’, it is likely that repetitions need not be as long as 15 seconds and that likely an effective volume and frequency of training are greater than typically recommended by ‘super slow’ advocates. Effective protocols may be more similar to ones originally advocated by Arthur Jones decades ago but with much greater attention to form, a longer time under load, and less concern with the use of great amounts of resistance. There also is one major caveat. Different protocols and different TUT’s may produce similar outcomes, as noted, because the all have a common critical component. They all involve training to volitional fatigue that appears to optimize motor unit recruitment. However, current data do not support the notion every single possible training variable (see the list of 13 noted earlier) and nuance result in different kinds of strength, endurance, power, and muscular hypertrophy adaptations. ?
